This is a proposal to isolate and determine the structure and the mechanism of action of four membrane transport systems: the (Na ion plus K ion) dependent adenosine triphosphatase involved in cation pumping; the glucose transport system which carries out facilitated diffusion of sugars; the anion transport system in human erythrocyte membranes involved in exchange diffusion of anions; and the adenylate cyclase system involved in hormone interactions. Finally, it is planned to characterize the erythrocyte membrane fibrous proteins involved in stabilization of the membrane.